ipvsadm lists a few hosts by IP only, rest by name

We use keepalived to manage our Linux Virtual Server (LVS) load balancer. The LVS VIPs are setup to use a FWMARK as configured in iptables.

 virtual_server fwmark 300000 {
    delay_loop 10
    lb_algo wrr
    lb_kind NAT
    persistence_timeout 180
    protocol TCP

    real_server 10.10.35.31 {
        weight 24
        MISC_CHECK {
            misc_path "/usr/local/sbin/check_php_wrapper.sh 10.10.35.31"
            misc_timeout 30
        }
    }

    real_server 10.10.35.32 {
        weight 24
        MISC_CHECK {
            misc_path "/usr/local/sbin/check_php_wrapper.sh 10.10.35.32"
            misc_timeout 30
        }
    }

    real_server 10.10.35.33 {
        weight 24
        MISC_CHECK {
            misc_path "/usr/local/sbin/check_php_wrapper.sh 10.10.35.33"
            misc_timeout 30
        }
    }

    real_server 10.10.35.34 {
        weight 24
        MISC_CHECK {
            misc_path "/usr/local/sbin/check_php_wrapper.sh 10.10.35.34"
            misc_timeout 30
        }
    }
}

http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.fwmark.html

[root@lb1 ~]# iptables -L -n -v -t mangle
Chain PREROUTING (policy ACCEPT 182G packets, 114T bytes)
 190M  167G MARK       tcp  --  *      *       0.0.0.0/0            w1.x1.y1.4       multiport dports 80,443 MARK set 0x493e0 
  62M   58G MARK       tcp  --  *      *       0.0.0.0/0            w1.x1.y2.4       multiport dports 80,443 MARK set 0x493e0 


[root@lb1 ~]# ipvsadm -L
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
FWM  300000 wrr persistent 180
  -> 10.10.35.31:0                Masq    24     1          0         
  -> dis2.domain.com:0                Masq    24     3          231       
  -> 10.10.35.33:0                Masq    24     0          208       
  -> 10.10.35.34:0                Masq    24     0          0 

At the time the realservers were setup, there was a misconfigured dns for some hosts in the 10.10.35.0/24 network. Thereafter, we fixed the DNS. However, the hosts continue to show up as only their IP numbers (10.10.35.31,10.10.35.33,10.10.35.34) above.

[root@lb1 ~]# host 10.10.35.31 31.35.10.10.in-addr.arpa domain name pointer dis1.domain.com.

OS is CentOS 6.3. Ipvsadm is ipvsadm-1.25-10.el6.x86_64. kernel is kernel-2.6.32-71.el6.x86_64. Keepalived is keepalived-1.2.7-1.el6.x86_64.

How can we get ipvsadm -L to list all realservers by their proper hostnames?